Method of making fiber board



- July 3, 1928. 1,675,666

W. M. SHOEMAKER, JR

METHOD OF MAKING FIBER BOARD Filed Dec. 27, 1926 v 5 Sheets-Sheet l ATTORNEY July 3, 1928.

W. M. SHOEMAKER, JR

METHOD OF MAKING FIBER BOARD Filed Dec 27, 1926 s Sheets-Sheet 2 QOOOOOOII. I T

hawk. 3 WM m $6 l I l l l l I II 11v VENTOR 1 and mHflMema/fer 1/7, W MWA TTORNEY July 3, 1928.

w. M. SHOEMAKER, JR

METHOD OF MAKING FIBER BOARD Filed Dec. 27, 1925 I5 Sheets-Sheet [NVENTOR ATTORNEY li atented July 3, 1928.

UNlTED STATES PATENT OFFICE.

WILLIAM M. SHOEMAKEB, JR., OF KENNETH. SQUARE, PENNSYLVANIA, ASSIGNOB TONATIONAL VULCANIZED FIBRE COMPANY, 01' WILMINGTON, DELAWARE, A COR-PORATION OF DELAWARE.

' METHOD OF MAKING FIBER BOARD.

Application filed December 27, 1926. Serial No. 157,218.

The present invention relates to the manufacture of fiber sheets orfiber board quite generally known in the trade as vulcanized fiber, inwhich a plurality of thin sheets of cellulosic material may be united toform a single sheet; or a single sheet may be employed which may berolled up over a heated drum or cylinder to produce a sheet of thethickness required.

Heretofore in the manufacture of fiber board the practice has been, asfar as I am aware, to subject thin sheets preferably of unsized cottoncellulose paper, to the action of a suitable metallic salt such as zincchloride in solution in water by passing the said sheets through such asolution having a strength of about 70 Baum and at a temperature rangingfrom ordinary room temperature to about 35 C, and conducting thesheets'from the said solution directly to and between heated drums orcylinders by means of which the said'sheets are subjected to pressureand heat and union thereof effected to form a single sheet.

In the manufacture of fiber boardit is necessary, after the impregnationof the sheets with a suitable solution, usually consisting of a suitablechemical in water, that heat be applied thereto. Heretofore the heatedpressure drums or cylinders or other pressure means, between which thesheets havebeen compressed to effect union thereof, have been reliedupon for supplying the heat necessary to be applied to the said sheets.By this method the heat is applied directly only to the outer surfacesor sides of the top and bottom plies or sheets of the plurality ofsheets being unlted. In

order that there may be no question but that the sheet or sheets whichenter into the final product shall have been subjected to the sametreatment it is desirable that heat be applied to each sheet separatelyreferably, though not necessarily, to both s1 es thereof sinmltaneously.As a result of so applym the heat and thereby effecting uniformity 0application of heat to each sheet a product having uniform texturethroughout 1s assured.

The general object, therefore, of the present invention is to provide anovel method by the employment of which a plurality of sheets ofcellulosic material may be united to form a fiber board or fiber sheethaving improved structural characteristics and qualities.

Other and further objects of the invent1on are to provide a novel methodby the employment of which both sides of each of a plurality of sheetsof cellulosic material WlllCll may be united to form a single sheet maybe subjected to the action of heat at a temperature requisite to and forthe manufacture of fiber board, or vulcanized fiber as it is generallycalled in the trade; to provide a novel method wherein and whereby therespective plies orsheets ofcellulosic material are each subjected tothe same degree of temperature; to provide a novel method wherein andwhereby the plies or sheets which form the interior of the final productshall have been subjected to the same degree of temperature as thesheets forming the outer sides or surfaces thereof; and to provide otherimprovements as will be set forth hereinafter.

As a result of the application of heat at the temperature required tothe separate sheets which are to be united I have discovered that a moresatisfactory product may be obtained than has been obtainable .by theemployment of the methods heretofore known and employed in themanufacture of fiber board.

'In describing the method embodying my invention it is preferable thatreference be made to an ap aratus which may be em ployed for han lingthe sheets of cellulosic material and effecting the necessary treatmentthereof and the uniting of the same to form relatively thick sheets offiber boa-rd. Accordingly, therefore, I have invented and designed anapparatus of novel construction whlch may be employed in the carryingout of the method invented by me and to which reference will be made inconnection with the description of the said method.

In the accompanying drawings I have illustrated one form of apparatusembodying the novel means invented b me for forming one or a luralit ofs eets into fiber board or vu canize fiber and to which I shall refer indetail in the following descri tion.

11 the rawings.

Fig. 1 is a view in side elevation of a portion of a machine orapparatus by the stituting a part of the means for heating able chemicalsuch as zinc chloride or other separately and individually the sheets ofcellulosic material. the union of which is to be effected, the said viewshowing a portion of the heating means in plan; and

Fig. 4 is a transverse sectional view taken on the line 4-4 of Fig 3.

In the drawings I have shown a magazine 10 or supply of plies or sheetsof cellulosic material, a tank 11 containing a suitsuitable metallicsalt or other chemical in solution in a suitable solvent. such as water,for impregnating the said sheets, a heating means 12 for the applicationofheat at the requisite temperature simultaneously to both sides of eachof the chemically treated plies or sheets, and a compressing means 13wherein the plies or sheets are superposed and merged by pressure into asingle sheet. This sheet, after the usual treatment to effect removal ofthe chemical with which the respective sheets were impregnated orsaturated and after having been dried, becomes what is known as fiberboard or vulcanized fiber. The plies or sheets usually consist of cottoncellulose but may consist of cellulose obtained from other sources andmay also consist of a mixture of cellulose obtained from differentvegetable sources.

Themagazine 10 preferably is of open frame-construction having journals1 1 suitably mounted on side bars 14" to rotatably support the rolls 15of paper (cellulose sheets) which depend in number upon the number ofsheets or plies to be used to form the finished product; that is, thefiber board sheet. Thus, if a five-ply material is to be made only fiverolls 15 will be used; while if a fifteen-ply material is to be madethere will be fifteen rolls 15 in operation.

' The solution 16 gpreferably ofzinc chlo ride or other suitab e metalsalt) of suitable strength, say around Baum, in the tank 11 is providedin sufficient quantity to insure the complete immersion of the maximumnumber of plies or sheets which may be employed. The temperature of thesolution as employed may range from ordinary room temperature to atemperature of about 35 C. One end of the tank 11 is of arc shape asshown in order to provide clearance to permit lateral movement of thepivoted spacing guide cage 17 toward the left in Fig. 2 of the drawings,and upwardly to a position above thetank 11 to facilitate the insertionor threading of the plies or sheets 21 bet-ween the spaced guides 18and20 provided in two series located in two spaced upwardly convergingplanes, as shown in Fig. 2. Each guide of one series is located in aposition horizontally opposite that of the corresponding guide in theother series. After the sheets 21 have been threaded through the cage 17underneath opposing guides 18 and 20 and said cage is lowered into thetank 11 as shown in Fig. 2 the said sheets, as they travel forward, areheld in spaced substantially parallel relation to each other while inand as they pass through the bath or solution 16. The parallelrelationship is unimportant but it is important that they be held spacedfrom each other. It will be noted that the upper plies or sheets 21remain in the said bath or solution for a shorter period than do thesuccessive lower plies or sheets. It follows, therefore, that the speedof travel or movement of the sheets through the bath or solution must besuch as to allow suflicient time for the necessary impregnation of theuppermost sheets. This is a practical matter 2nd may be readilycontrolled or provided "To provide for the operation of the cage 17 itis mounted upon a swinging frame 22 which includes lifting arms 23 and achain hoist 24 whereby it can be swung out of and above the bath 16 forthe purpose previously.

stated.

In order to effect uniform heating of eachply or sheet 21. after itspassage through the bath 16 and prior to the union of the'shcets, theheating means 12 is provided. In its preferred form the said meansconsists of a plurality of heating units each of which comprises plates25 and 27 spaced from and in parallel relation to each other to form awide thin chamber as indicated-in Figs. 2, 3 and 4 of the drawings Forsupplying a heating medium to the respective chambers formed by thespaced plates 25 and 27 I have provided in each chamber a tubularstructure comprising side members 30 and 31 which are connected bycross-wise extending tubes 32 having openings 32' in the opposite sidesthereof. For heating the respective units steam is supplied to the pipesof the tubular frame structure of each unit and escapesthroughthe'openings in the cross tubes 32 and through openings 33 in theinner sides of the side tubes 30 and 31 into the chamber between theplates 25 and 27 and is condensed so that the said chamber becomesfilled with water at a temperature sufficient to supply the heat to beapplied to the respective sheets 21 as they travel through thepassageways 26 between the adjoining units. The temperature to which thesaid sheets may be subjected may range from about 38 C to about 93 C.The upper surface of the plate 25 of each unit preferably is slightlyconvex as shown. As

the respective sheets 21 are conducted through the passageways 26 theycontact with the convex surfaces of the plates 25 of the respectiveunits. The adjoining units are located close together so that the spaces26 through which the sheets travelers quite narrow. The heat, in theconstruction shown, is applied to the lower sides of the respectivesheets as they pass through the passagewt Iys' 26 by conduction from theplates 25 wit which they are in contact, while to the opposite sidesthereof heat is applied by radiation from the plates 27 of adjoiningunits. The plates 27 of adjoining units are so close to the upper sidesof the sheets as they travel through the spaces 26 that each side ofeach sheet is subjected simultaneously to heatat substantially the sametemperature. The'sheets being quite thin it follows that the particlesthereof are affected in substantially equal degree. The result of thisis that the characteristics of therespective sheets are the same orsubstantially the I same so that when they are combined into a singlesheet a product having uniform and improved characteristics andqualities as compared with products as heretofore manufactured is theresult.

Although it is preferred to apply heat to both sides of" each sheet asabove described, it is to be understood that my invention comprehendsthe application of heat to one side only of each sheet. When the saidsheets are thin it is apparent that such application usually wouldaccomplish the result desired.

In the case of sheets of c'ellulosic material of relatively lowabsorbtivity usually char-. acterized as hard, it will be found thatuponthe passage of the same through the solution the outer portions of theopposite sides thereof will be sufficiently impregnated to causeefficient union thereof upon their passage between the compressioncylinders or drums 35 and 36. It maybe that the portions of such sheetsbetweenthe said outer )ort-ions upon the o iposite sides thereof will Ib not be impregnate'c, or only partially impregnated, but such acondition will not interfere with the efficient union of adjoFningsheets. All of the sheets which maybe passed through the solution andthereafter united will have been subjected to identical treatment andwill have substantially the same characteristics.

The respective heating units are supported in spaced relation to eachother to provide the passageways 26, to which reference has been made,by the interconnection of the tubes (through which the heating medium issupplied to the respective units) between the said units, and theheating'means 12 as a whole is supported by the common supporting frame34.

In undergoing the treatment as thus far described impregnation of thesheets with the salt solution or other chemical solution in the tank 11and gelatinization thereof have been effected. They are now in conditionand ready to be superposed and subjected to pressure to effect unionthereof to formthe product desired, namely. fiber board or vulcanizedfiber as it is generally called.

For effecting union of the sheets which" to the pressure means 13comprising the heated cooperating )ressure drums or cylinders 35 and 36.y reason of the fact that the individual plies or sheets have beensubjected already to the action of heat by the heating means 12 it isnot necessary that these drums or cylinders 35 and 36 be maintained atas high, a temperature as heretofore has been the practice. The sheetsto be united arev conducted over the (lltlil'l or cylinder- 35, around aportion thereof, and between the said drums or cylinders 35 and 36 andthereby subjected to heavy pressure in known manner 'whcreby unionthereof is effected to form a sheet having a combined thickness of theunited plies or sheets. The sheet'or board formed by the uniting of thesaid plies or sheets is led away from the pressure drums as indicated at37 and may be cut into sections of such length as may be desired. Thesesections then are subjected to the usual treatment to effect removal ofthe chemical with which the respective sheets were impregnated as theymoved or passed through the solution 16 in the tank 11. After theremoval of such chemical, usually zinc chloride, the sheets are dried.However, the present invention is not concerned with the treatment ofthe sheets after they leave the pressure means 13.

In the methods and apparatus heretofore employed in the manufacture offiber board or vulcanized fiber the thickness of the sheets constitutingthe final product which might be manufactured has been restricted orlimited. Such restriction and limitation h ave been due to the fact thatthe heated pressure drums or cylinders corresponding to those designatedand 36 in the drawings have been relied upon to furnish the heatnecessary to be applied to the respective sheets in order thatsatisfactory union thereof might be effected. As already indicated, whenthe pressure drums or cylinders were relied upon to supply the requiredheat the application thereof has been made only to the outer sides ofthe outer plies. It is apstrictions and limitations because of theapplication of heat at the required temperature to eachsheet of a-,plurality of sheets which areto be united prior to the bringing of thesame together between the pressure cylinders or drums of the compressionmeans by which union thereof is effected.

An important and essential feature of my invention consists in theapplication of heat to the respective sheets which are to be united,preferably simultaneouly to both sides of each sheet, after the same hasbeen impregnated with the solution of salt or other chemical 16 andprior to the bringing of the said sheets together and the subjectionofthe same topressure within the compression means 13 to effect unionthereof. I

While I have illustrated a plurality of plies or sheets treated andunited to form a single sheet of 'fiber board it will be under stoodthat my invention may be employed in the formation of a fiber boardsheetlfro'm .a single thin sheet of cellulosic material of propercharacter by winding the same up onthe drum or cylinder 36 to' obtainthe required thickness. The removal of such sheet from the drum or.cylinder ma be effected in known manner by slitting t e same. a

It is to be understood that the invention is not limited to apparatus ofthe" specific con-- struction illustrated herein and that the-saidinvention is susceptible of embodiment in apparatus of other forms ofconstruction than that shown, and also that the method invented by memay be practised and carried out by means other than that shown in thepresent apparatus.

Having thus described my invention, what I claim and desire tosecure byLetters Patent is:

'1. The method of forming a fiber sheet from a plurality of sheets ofcellulosic' material, WlllCll consists in impregnating a plurality ofsaid sheets of cellulosic material thereof; a a,

:5.- The method of forming fiber board,

metallic salt in solution to efiect impregnation thereof, thereaftersubjecting the respective sheets to heat at the requisite tem- 'peraturewhile holding the said sheets in spaced relation to eachother, andthereaf ter superposingthe said sheets and applylng,

pressure thereto to effect union thereof. A

The method of forming fiber board from a' lurality of sheets ofcellulosi'c material, whichcomprises the subjection of the said sheetsto the action of'a suitable chemi cal solution in water'to effectimpregnation thereof, causing the said sheets to move through a zone ofheat at requisite temperature, holding the said sheets while'movingthrough said zone "in spaced relation with respect each other,thereafter bringing the said'sheets'together, and subjecting the same topressure to effect union thereof.

4. The method of forming fiber board,

which consists in passing a plurality of sheetsiof cellulosic materialthrough a water solution-of a suitable metallic salt, .con-

ducting the said sheets in spaced relation.

to eachother away from the said solution andgwhile so spaced applyingheat at re 'uisite' temperature simultaneously to bot sides of eachsheet, and thereafter'brin'ging the said sheets together and ei fectingunion which consists in conducting a plurality of 'cellulosic sheets inspaced relationto each other through a solution of zinc chloride,

thereafter supporting saidsheets in spaced relation to each other andapplying heat at requisite temperature to each individual sheet toefiect'the necessary gelatinization,

and thereafter bringing the said sheets together and effecting unionthereof to form a single sheet. I i

I 6L The method which comprises the-steps of impregnating a web ofcellulosic material with a suitable gelatinizing agent, moving said webthrough a heat zone wherein heat at substantially the same temperatureis applied simultaneously to both sides thereof,

and laminating said web, the steps being performed successively andcontinuously.

Signed at Wilmington, county of New Castle, State of Delaware, this 23rdday of December, 1926. I

WILLIAM M. "SHOEMAKER, JR.

